[swift-evolution] Add @noescape to output parameter of 'UnicodeCodecType.encode'

[rintaro ishizaki]

Currently, all callers of this method in the Standard Library
assume `output` parameter has @noescape semantics.
So, I think, we can/should mark it with @noescape.
Is there a reason why it isn't?

public protocol UnicodeCodecType {

    // ...

    static func encode(
        input: UnicodeScalar,
        @noescape output: (CodeUnit) -> Void)
}

--
Rintaro Ishizaki